On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 371 
if the diagnosis of these genera be correct, it is at once distinguished by the 
direction of the line dividing the base from upper part of the spine, which in 
Drepanacanthus (“ Geol. Surv. Illinois,” Vol. IT., p. 121) “slopes upward at an angle 
of 45° from the concave to the convex margin,” so that the spine must have had an 
inclination forwards instead of backwards. In the genus at present described the 
spine was inclined in the ordinary way, backwards. 
In the “ Fauna du Caleaire Carbonifere de la Belgique,” L. G. de Koninck describes 
a genus Stichacanthus. In many respects it appears to be closely related with this, 
but it differs in having all the tubercles arranged in longitudinal lines and attached, 
the one to the other, by a prolongation of the surface ; they have also the posterior 
border armed with a row of small oblique teeth directed towards the base. Mons. 
de Koninck states that there is a specimen of this ichthyodorulite at the British 
Museum. I have not observed, during recent visits to the collections at Cromwell- 
road, such a specimen as he describes. 
Chalazacanthus verrucosus, Davis. 
(Pl. XLVIIT., fig. 13.) 
Spine, about six inches in length, and less than one inch wide at its greatest 
breadth midway between the two extremities, moderately curved, the anterior 
margin more so than the posterior, the two somewhat rapidly converging near the 
apex. Transverse section triangularly cone-shaped, sides much compressed and 
about twice the length of the base, latter hidden by matrix, the two sides meet 
anteriorly and form an obtusely rounded surface without keel ; the basal portion of 
the posterior surface forms a deep cavity ; higher it 1s enclosed and extends nearly 
the whole length of the spine. Base imperfect, slightly tapering, osseous, striated. 
Length along the anterior margin 1°8 inches, and about three inches posteriorly. 
Line dividing the basal from the exposed part decidedly oblique with convex 
curvature towards the base. The striated character uf the base is continued some 
distance along the posterior margin. Exposed surface ornamented by a large 
number of tuberculations without definite arrangement, occasionally forming into 
oblique rows, at other places longitudinal ones ; the tubercles are less distinct near 
the apex of the spine. 
A second specimen, in the Enniskillen collection, probably belongs to this species, 
it is imperfect and indistinct, but appears to conform generally to the description 
given above. In transverse section it is much less compressed laterally, and the 
external tuberculation is more prominently developed. It is from the Mountain 
Limestone of Armagh. 
Formation and locality : Lower Carboniferous Limestone, Black Rock, Avon, Bristol. 
Ex coll. British Museum. 
